Microbial competition for phosphorus limits the CO2 response of a mature forest

Mingkai Jiang, Kristine Y. Crous* (Corresponding author), Yolima Carrillo, Catriona A. Macdonald, Ian C. Anderson, Matthias M. Boer, Mark Farrell, Andrew N. Gherlenda, Laura Castañeda-Gómez, Shun Hasegawa, Klaus Jarosch, Paul J. Milham, Rául Ochoa-Hueso, Varsha Pathare, Johanna Pihlblad, Juan Piñeiro, Jeff R. Powell, Sally A. Power, Peter B. Reich, Markus RieglerSönke Zaehle, Benjamin Smith, Belinda E. Medlyn, David S. Ellsworth

*Corresponding author for this work

Research output: Contribution to journal/periodicalArticleScientificpeer-review


The capacity for terrestrial ecosystems to sequester additional carbon (C) with rising CO2 concentrations depends on soil nutrient availability1,2. Previous evidence suggested that mature forests growing on phosphorus (P)-deprived soils had limited capacity to sequester extra biomass under elevated CO2 (refs. 3,4,5,6), but uncertainty about ecosystem P cycling and its CO2 response represents a crucial bottleneck for mechanistic prediction of the land C sink under climate change7. Here, by compiling the first comprehensive P budget for a P-limited mature forest exposed to elevated CO2, we show a high likelihood that P captured by soil microorganisms constrains ecosystem P recycling and availability for plant uptake. Trees used P efficiently, but microbial pre-emption of mineralized soil P seemed to limit the capacity of trees for increased P uptake and assimilation under elevated CO2 and, therefore, their capacity to sequester extra C. Plant strategies to stimulate microbial P cycling and plant P uptake, such as increasing rhizosphere C release to soil, will probably be necessary for P-limited forests to increase C capture into new biomass. Our results identify the key mechanisms by which P availability limits CO2 fertilization of tree growth and will guide the development of Earth system models to predict future long-term C storage.
Original languageEnglish
Publication statusPublished - 05 Jun 2024


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